1. Field of Use
The present invention relates to a method for preserving fresh cut flowers or plant cuttings.
2. Description of the Background
It has been known for a number of years that horticultural products, including flowers, fruit and vegetables in a controlled atmosphere, are sensitive to the temperature, concentration of carbon dioxide and oxygen gases and humidity in spaces where these materials are stored. Hence, conventional methods for preserving horticultural products have involved the regulation of these factors. For example, British patent 1,255,700 describes a method of preserving horticultural products wherein the products are stored in an enclosed space containing an artificial atmosphere which is contained inside a cold chamber to effect indirect refrigeration of the products. The method of this patent also entails the circulation of an artificial atmosphere within the contained space, the composition, humidity and temperature of which is controlled externally.
Although some success has been attained with this method, in general, the use of refrigeration for the preservation of horticultural products either in transportation or in storage is quite expensive, and, thus, undesirable.
More recently, gas packaging has been used to extend the shelf-life of fresh food products. While gas packaging techniques have been used in an attempt to extend the shelf-life of other products such as cut flowers or plant cuttings, it is found that the results obtained thereby are inadequate.
In gas packaging, gases such as carbon dioxide or sulfur dioxide are used in the effort to preserve fresh cut flowers or plant cuttings. Unfortunately, the tolerance of flowers or plant cuttings to elevated partial pressures of these gases is quite low.
It is known that by lowering the concentration of oxygen, a longer survival of plant material can be effected due to the reduction in respiration rate. Hence, by exposing fresh cut flowers or plant cuttings to carbon dioxide or sulfur dioxide a minor shelf-life extension is obtained in some cases, however, in most cases, little preservation effect is obtained as the vegetal deterioration is initiated and activated by the production and release of ethylene in the plant tissues.
When fresh cut flowers or plant cuttings are exposed to ethylene, initially the vegetal material changes color by yellowing of the leaves or petals. Thereafter, the vegetal material acquires a burned appearance, whereinafter ultimate necrosis of the vegetal material occurs. At present, no gas or gas mixture or gas technique has demonstrated an ability to reduce or control the production of ethylene and its effects on plant material. Hence, producers of fresh cut flowers or plant cuttings have relied primarily on temperature control or ethylene scavengers to avoid the build-up of ethylene within packages containing the plant material. Although it is possible to decrease the production rate of ethylene by decreasing the temperature, ethylene production by the vegetal material is not entirely suppressed. Moreover, when the plant material is subjected to an unexpected increase in temperature, ethylene production rapidly resumes and irreversible damage to the appearance of the plant material is observed.
Although chemical scavengers are effective in absorbing ethylene released by plants in their packages, such scavengers do not have any effect on biochemical ethylene production at the cellular level. Hence, ethylene scavengers are only useful to limit the reabsorption of ethylene by the non-ethylene producing portion of the vegetal material.
Hence, a need continues to exist for a means by which the biochemical production of ethylene, itself, may be decreased, in order to improve the shelf-life and color of fresh cut flowers or plant cuttings.